View source for ST-HL-AE-5780, Forwards Response to 970912 RAI Re GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design- Basis Accident Conditions. W/38 Oversize Drawings

{{Adams
| number = ML20199B038
| issue date = 11/11/1997
| title = Forwards Response to 970912 RAI Re GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design- Basis Accident Conditions. W/38 Oversize Drawings
| author name = Thomas S
| author affiliation = HOUSTON LIGHTING &amp; POWER CO.
| addressee name = 
| addressee affiliation = NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
| docket = 05000498, 05000499
| license number = 
| contact person = 
| document report number = GL-96-06, GL-96-6, ST-HL-AE-5780, NUDOCS 9711180194
| package number = ML20199B043
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE
| page count = 15
}}

=Text=
{{#Wiki_filter:The Light c o mp a ny South Temas Prohct Dectric Generatlog                               P. O.Station Bom 289 Wadsworth, Temas 77483 llouston 1,Ighting & Power November 11, 1997 ST-HL-AE-5780 File No.: G03.08 10CFR50 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Units I and 2 Docket Nos. STN 50-498 STN 50-499 Response to Request for Additional Information Regarding Generic Letter 96-06," Assurance of Equipment Operability and Containment intecrity Durine Desien-Basis Accident Conditions"

==Reference:==
Correspondence from Thomas W. Alexion, Nuclear Regulatory Commission, to William T. Cottle, Houston Lighting & Power Company, dated September 12,1997 Pursuant to the reona" for additional information referenced above, ti.e South Texas Project submits the attached responses to the Nuclear Regulatory Commission's questions regarding our response to Generic 1Aer 96-06, " Assurance of Equipment Operability and Containment Integrity During Design Basis Accident Conditions."
This letter provides the information requested by the Nuclear Regulatory Commission to complete the review of Generic Letter 96-06, and includes detailed information regarding the calculations which support the South Texas Project response to the Generic Letter.
This letter is not considered to contain any commitment beyond a description of how the calculations in question were performed.
If there are any questions, please contact either Mr. K. D. House at (512) 972-8922 or me at (512) 972-7162.
                                                                                /n Cl_
S. E. Thomas 9711100194 971111 "
p)
DR     ADOCK O               8                                          Manager                                   j
                                   ~
Design Engineering PLW/
Attachments: 1) Response to Request for Additional Information Regarding Generic Letter 96-06
: 2) Condition Report Engineering Evaluation No. 96-12151-27
: 3) Cross-Reference Table
: 4) Drawings for Piping and Valves                               [\,l]{\]{\$[l)})\[\f!\ !!b!,k Project Manager on Behalf of the Participants in the South Temas Project
[($1y g gyj \ h@                          \ ri     {Tj [f]         h! f(    C*

llouston Lighting & Power Company South Texas Project Electric Generating Station                          ST-HL-AE-5780 File No.: G03.08 Page 2 c:
Ellis W. Merschoff                                   Rufus S. Scott Regional Administrator, Region IV                    Associate General Counsel U. S. Nuclear Regulatory Commission                  IIouston Lighting & Power Company 611 Ryan Plaza Drive, Suite 400                      P, O. Box 61067 Arlington, TX 76011-8064                             Houston, TX 77208
* Thomas W. Alexion                                  Institute of Nuclear Power Project Manager, Mail Code: 13H3                       Operations - Records Center U. S. Nuclear Regulatory Commission                  700 Galleria Parkway Washington, DC 20555-0001                            Atlanta, GA 30339-5957 David P. Loveless                                    Dr. Bertram Wolfe Sr. Resident inspector                               15453 Via Vaquero c/o U. S. Nuclear Regulatory Comm.                   Monte Sereno, CA 95030 P. O. Box 910 Bay City, TX 77404-0910                              Richard A. Ratliff Bureau of Radiation Control J. R. Newman, Esquire                                Texas Department of Health Morgan, Lewis & Bockius                              1100 West 49th Street 1800 M Street, N.W.                                  Austin, TX 78756-3189 Washington, DC 20036-5869 M. T. Hardt/W. C. Gunst                              J. R. Egan, Esquire City Public Service                                  Egan & Associates, P.C.
P. O. Box 1771                                       2300 N Street, N.W.
San Antonio, TX 78296                                Washington, D.C.
J. C. Lanier/M. B. Lee                               *U. S. Nuclear Regulatory Comm.
City of Austin                                       Attn: Document Control Desk Electric Utility Department                          Washington, D.C. 20555-0001 721 Barton Springs Road Austin, TX 78704 Central 1 ower and Light Company ATTN: G. E. Vaughn./C. A. Johnson P. O. Box 289, Mail Code: N5012 Wadsworth, TX 77483
* Above copies distributed without Attachment 4, except as noted by asterisk.
J

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ATTACHMENT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING GENERIC LETTER 96-06
                          - ,         . n.-

Attachment 1 ST-IIL-AE-5780 Page 1 of 12 South Texas Project Units 1 and 2 Resoonse to Request for Additional Information Recardine Generic Letter 96-06 OUESTION 1:
The January 28,1997, submittal, indicated that nine piping runs susceptible to thermally induced overpressure were determined to be acceptable based on the valve design. These piping runs contained either spring-loaded valves that form isolation barriers or valves that will self-relieve through leakage that form isolation barriers. In the submittal, it was stated that these valves would relieve water to preclude an overpressure condition.
Provide the following information for each piping run evaluated in this manner:
OUESTION la:
Describe the applicable design criteria for the piping and the valves. Include the required load combinations.

===RESPONSE===
The piping and valves were evaluated in accordance with the pressure and stress criteria for faulted conditions (Level D service limits) as specified in ASME B&PV Code, Section 111 Subsection NC,1974 Edition through Winter 1975 Addenda. Other addenda used are: Subsections NC-3611.2 and NC-3500, Table NC-3521-1 of Winter 1976 Addenda.
The following load comnination was used:
Pressure + Dead Weight + Occasional loads (faulted)
OUESTION lh; Provi<ie a drawing of the valve. Provide the pressure at which the valve was determined to hi. off its seat or leak and describe the method used to estimate this pressure. Discuss any sources of uncertainty associated with the lift off pressure.

===RESPONSE===
Drawings of the valves are provided in Attachment 4. For cross-reference purposes, a table is provided in Attachment 3 identifying the valve numbers and the associated drawing numbers for each case evaluated.
For spring-loaded air-operated valves that were credited for overpressure protection, the pressure at which the valve was determined to lift offits seat was calculated based on its actuator benchset pressure, actuator diaphragm effective area, and valve plug cross-section area. The actuator benchset pressure is the field measured value at which the

Attachment i ST.HL-AE-5780          l Page 2 of 12           l valve starts to move off its seat against the spring and packing forces as air pressure is  i applied to the valve diaphragm. The benchset pressures are documented in the South          i Texas Project Valve Scaling Sheets and are included in Attachment 3.                        j In most cases, a pressure value higher than the actual benchset pressure was conservatively used in the evaluation in order to account for uncertainty. In the remaining case (Case #5, Attachment 3),16 psig is used f'r both the actual benchset pressure and the benchset pressure used. This is acceptable because the uncenainty associated with the benchset pressure is expected to be negligible due to these air-operated valves being small sampling valves that are operated frequently, Additional calculations are expected to be performed to determine if a design basis accident will result in pressures less than the actual benchset pressure, Credit for overpressurization protection provided by the spring-loaded air-operated valves may not be necessary pending the results of the final calculation.
Additional details are provided in Condition Repon Engineering Evaluation No. 96-12151-27 (Attachment 2).
OUESTION le:
Provide the maximum-calculated stress in the piping run based on th< 1 'imated lift off or leakage pressure.

===RESPONSE===
The maximum calculated stresses for all ten cases evaluated in Condition Report Engineering Evaluation No. 96-12151-27 (Attachment 2) are summarized as follows:
CASE NO,               I,INE NO.          MAXIMUM          AI,1,0WAHLE STRESS , PSI       STRESS , PSI GROUP 1:                                    (FAULTED) 1         3/4"-SI-1321-BB2             31,856              36,720 2            1"-PS-1005-BB2             23,234              37,680 3            1"-PS.1002-BB2           _ 30,686              37,680 4            1"-PS-1003-UB2             37,038              37,680 5           '" PS-10N-UB2
                              -                       35,194              37,680 6           . -ED-ll24-SB2 9,870              37,680 GROUP 2:
7          8"-RH-1204-KB2               26,762              37,680 8          8"-RH-1304 KB2               26,762              37,680 9            1"-PS-1016-BB2             30,204              37,680 10         3"-WL- 1009-RB2              14,839              37,680 l
l

Attachment 1 ST Hi-AB 5780 Page 3 of 12 The-maximum stress values were conservatively calculated by adding the new stress values to the existing stress values previously computed in the design calculations.
Additional margins are available because the highest stress value taken from the most limiting data point in the boundary of the design calculation was conservatively used.
The actual stress values of the data points located between the containment isolation valves are much lower.
OUESTION 2:
The January 28,1997, submittal, indicated that the reactor coolant pump drain tank line was insulated in order to maintain piping stresses within the allowable limits. Provide the following information for this piping run:
OUESTION 2a:
Provide the applicable design criteria for the piping and the valves. Include the required load combinations.

===RESPONSE===
The piping and valves were evaluated in accordance with the pressure and stress criteria for faulted conditions (12 vel D service limits) as specified in ASME B&PV Code, Section III Subsection NC,1974 Edition through Winter 1975 Addenda. Other addenda used are Subsections NC-3611.2 and NC-3500, Table NC-3521-1 of Winter 1976 Addenda.
The following load combination was used:
Pressure + Dead Weight + Occasional loads (faulted)
OUESTION 2h:
Provide a drawing of the piping run between the isolation valves. Include the lengths and thicknesses of the piping segments and the type and thickness of the insulation.
RESPONSfg Drawings of the piping runs and information concerning the piping and insulation are provided in Attachments 3 and 4. Refer to Case # 10 of Attachment 3 for information relating to the reactor coolant drain tank line.
00ESTION 2c:
Provide the maximum-calculated temperature and pressux for the pipe run. Describe, in detail, the method used to calculate these pressure and temperature values. This should

Attachment 1 ST HL-AE-5780 Page 4 of 12 include a discussion on the heat transfer model used in the analysis and the basis for the heat transfer coefficients used in the analysis.
RESf0NSE1 2.c.a    Maximum calculated temperature and pressure for the pipe run:
An evaluation of the maximum pipe temperature and pressure has been performed using the following initial conditions:
Tpgani, =          75 'F Pppanii =          150 psig Tconi     =        Temperature profile calculated in the LOCA analysis of record hconi     =        Condensing heat transfer coefficient calculated in the LOCA analysis of record Based on these initial conditions, the maximum temperature and pressure were determined to be:
T ino     =         128 *F.
P nu i
                    =        2690 psig.
The calculations performed to determine these values are being incorporated into the South Texas Project design basis.
2.c.h Method used to calculate these pressure and temperature values:
2.c.h.1 Methodology The methodology implemented by the South Texas Project to address pipe pressurization in isolated lines due to the heating of trapped fluid following a design basis accident is based on the methodology presented in Reference 1. Specifically, the calculations are based on Equation 19 of Reference 1 (reproduced below as Equation 1) and the assumption that mass is conserved in the isolated volume. Equation I presents the derivative of the pipe volume as a function of the change in pipe internal pressure and temperature with respect to time.
       ~                   ~          '
dV
-=
5n IW dp +  -
3nctLD' dT dt E,quation I
_16Et _ di          _
4    _
di Where V is the initial pipe volume, t     is time, L is the pipe length, D is the pipe inner diameter, t     is the thickness of the pipe, E is the modulus of elasticity of the pipe material, p is the trapped fluid pressure, a is the coefficient of thermal expansion of the pipe material, and T is the pipe temperature.

Attachment 1 ST.HL-AE-5780 Page 5 of 12 Assuming that the changes in pipe dimensions are negligible when compared to the changes in temperature and pressure, Equation 1 may be written as:
JV
    -=V
             ' 5D ' dp + 3a dT' Equation 2 dt       u 4Er. dt         dt ,
Where V = nD2 U4 Integrating Equation 2 with respect to time and rearranging the terms yields:
dV     S D dp + 3adT
   -=                                                                                Equation 3 V     4rE Assuming dV to be much smaller than V, Equation 3 becomes:
AV     5 D Ap + 3aAT
         =                                                                           Equation 4 V     4t E Therefore, a given increase in temperature and pressure results in a final piping volume that is independent of the order of pressurization and heating. Consequently, the expansion process can be treated in two independent steps: an expansion due to heating, and an expansion due to pressurization. Additionally, the volume of the fluid trapped inside the pipe section is assumed to be equal to the volume of the pipe section.
2.c.h.2 Expansion Due to Pipe Heating The isolated pipe section under consideration is assumed to begin inside containment, pass through the containment wall, and run for some distance outside containment. Th..
results in three distinct piping sections to be considered in the heat-up and pressurization analysis:
: 1. The section inside reactor containment (IRC).
: 2. The containment penetration, and
: 3. The sectiori outside reactor containment (ORC).
Assuming the occurrence of a design basis accident, the IRC pipe section is exposed to elevated temperatures, resulting in heat transfer from the containment atmosphere to the IRC pipe section. Ileat is conducted from the IRC pipe section through the containment penetration to the ORC pipe section. In order to determine thermal expansion of the pipe, heat tnmsfer from containment to the IRC pipe section must be determined followed by determining the heat transfer from the IRC pipe section to the ORC pipe section.
The following assumptions form the basis for the application of Equation 4 with respect to the heat transfer calculations being performed:
: a. The instantaneous heat transfer rau from the containment atmosphere to the trapped fluid in the IRC pipe section can be approximated by the steady state heat transfer rate through the pipe and insulation, if present.

Attachment i ST-HL-AIM 780 Page 6 of 12
: b. The convective heat transfer coefficient describing heat transfer from the inner surface of the pipe to the fluid within the pipe is assumed to be constant. The heat .
transfer coefficient can be approximated using an equation for natural convection from the outer surface of a horizontal cylinder.
: c. Buoyancy induced flow between the IRC and ORC pipe sections does not result in a change in water mass in these sections. IIeat transfer associated with the convective heat transfer that would occur due to buoyancy-induced flow is considered based on Reference 3. See Section 2.c.b.2.2.
2.c.b.2.1 IIcat Transhr from Containment to the IRC Volume lleat transfer from the containment atmosphere to the trapped fluid in the IRC pipe section is approximated by the steady state heat transfer rate as follows:
Tcm - Trac 4 ''' "                            r 9,8          r 9, + 2 e g,,,
in             In I                   < Di >         q     D.      >     I C_,
* h
* A.       2
* x
* kni. *L       2*x*ki L        hi
* As Where c/,,c       is the heat transfer rate from containment to the IRC volume, Tcom     is the containment temperature, Tinc     is the initial IRC volume bulk fluid temperature, Cw       is a multiplier applied to the external heat transfer coefficient and is based on NUREG-0588 (IWr nce 5),
ho       is the external heat trarm r coefficient, Ao       is either:
: a. the outer surface area of the insulation, for the insulated pipe case, or
: b. the outer pipe surface area for the un-insulated case, Do       is the outside diameter of the pipe, Da       is the inside diameter of the pipe, knre     is the thermal conductivity of the pipe material, L        is the length of the IRC portion of the pipe, t.
i       is the innlation thickness,
: k. i     is the thermal conductivity of the insulation material, h,       is the pipe inner surface heat transfer coefficient, and Ai       is the inner piping surface area of the IRC volume.
A multiplier of 4.0 is applied to the external heat transfer coefficient based on the guidance provided in Reference 5. The external heat transfer coefficient used in the pipe pressurization analysis is based on the condensing heat transfer coefficient calculated by the containment pressure / temperature analysis code for the LOCA analysis of record.
Based on Reference 2, the convective heat transfer coefficient inside the pipe (h,) is calculated for natural convection around a horizontal cylinder. The heat transfer coefficient is calcalated as follows:

Attachment 1 ST-HL-AE-5780 Page 7 of 12 h=k Nu I
Where k is the thermal conductivity of water, 1 is the inner diameter of the pipe, and Nu is the Nusselt number.
The Nusselt number is given for natural convection outside a horizontal cylinder on page 177 of Reference 2 as a function of the Grashof number and Prandtl number.
        - Nu = dGr Pr)*
Where c is a constant given as 0.53, Gr is the Grashof number, Pr is the Prandtl number, and n is given as 1/4.
From Reference 2, the Grashof number is calculated as follows:
Gr= Op'fATg  ,
Y Where L is the inner diameter of the pipe, p is the density of water, p is the isopiestic coefficient of thermal expansion water at the maximum expected temperature, AT is the maximum temperature difference between the fluid and the pipe wall, g is the gravitational constant (32.2 ft/sec 2), and is the viscosity of water.
Reference 2 also gives the Prandtl number as follows:
Pr =
k Where p is the viscosity of water, Cpis the specific heat of water, and k is the thermal conductivity of water.
2.c.b.2.2 IIcat Transfer from the IRC Volume to the ORC Volume Analysis of heat transfer from the IRC pipe section to the ORC pipe section is accomplished by defining a thermal conductor representing the containment penetration.
Consequently, heat transfer from the IRC to ORC pipe section can be evaluated using the following steady state heat transfer equation:
qonc= Tac- Toac
* akr a
* 7A ,a Where c/ one is the heat transfer rate between the IRC and ORC volumes, Tine is the initial IRC volume bulk fluid temperature,

Attachment i ST.ll!-AE5780 Page B of 12 Toac is the initial ORC volume bulk Guid temperature, Lry    in the IRC/ ORC conductor equivalent length (contain.nent penetration length),
kn.ia is the overall thermal conductivity of the equivalent penetration conductor, and Anna is the sum of the pipe and liquid cross sectional areas.
The thermal propedies of the equivalent penetration conductor are set to allow the conductor to simulate both the conduction through the pipe and '.he convective heat transfer in the water associated whh buoyancy-driven counter current nows in the penetration. Development of the thermal conductivity value for the equivalent conductor is based on Reference 3 and the simplifying assumption that the temperature gradients through the steel and liquid are similar.
Therefore, the overall thermal conauctivity of the conductor can be defined as:
kua = l>Aw a *()/(1/k,qA,) + 1/(1/koA ))
Where      ktna    is the overall thermal conductivity of the equivalent penetration conductor, L       is the length of the penetration, Ana is the sum of the pipe and liquid cross sectional areas, k,y     is the equivalent thermal conductivity of the water associated with buoyancy driven f;ows through the penetration, A,      is the cross sectional area of the water in the pipe, ko      is the thermal conductivity of the pipe material, and Ao      is the cross sectional area of the pipe material.
Reference 3 identifies a heat transfer correlation that can be used to estimate the effect of buoyancy induced flows through the penetration based on natural circulation in horizontal piping. Ilased on the Reference 3 correlation, the Nusselt number for fully developed natural circulation in a horizontal piping section with differently heated ends and a Rayleigh number greater than or equal to 3.0x 10' is calculated as follows:
Nu = 0.32*(llri)Ra"25 Where Nu is the Nusselt number for the flow, L is the length of the pipe, ri is the pipe inner radias, and Ra is the Rayleigh number which is defined as:
Ra = (g[lr/AT)/(ap) where      g is the acceleration of gravity,

Attachment i ST ill AIM 780 l' age 9 of 12 p is the coefficient of volumetric expansion of water, re is the inner radius of the pipe.
AT is the difference in the end temperatures, u is the thermal diffusivity of water, and is the Kinematic viscosity of water.
Given ths the heat transfu rate through the water portion of the equivalent conductor must be equal to the convective heat transfer rate through both ends of the pipe, the equivalent water thermal conductivity of the equivalent conductor can be determined as follows:
hAAT = ky AAT/L and h=Nu k./L, or Nu k. AAT/L = kmAAT/L Where h is the convectivt heat transfer coefficient associated with the water, kmis the equivaler.t thennal conductivity of the water associated with buoyancy.
driven flows thnwgh the penetration, Nu is the Nusselt Num',er, k, is the thermal conduct!vity of water, A is the cross sectional area of the penetration, AT is the difference in the temperature in the IRC and ORC pipe sections, and L is the totallength of the pipe.
Solving for the equivalent thernal conductivity of the water through the penetration estimating buoyancy-induced flows yields:
ky = Nu
* k.
2.c.h.2.3 IRC Pipe Section Temperature Change The evaluation of the temperature change in the IRC pipe section is based on the assumption that the liquid and pipe are at the same temperature. Therefore, the following equation is used to evaluate the temperature change for the liquid in the IRC pipe section:
: r.          . 3
* Al Ginc~(}UnC ATinc =                                                                                Equation 5 (m.
* c,.. .),,c Where [pnc is the heat transfer rate from containment to the IRC volume, c/ onc is the heat transfer rate between the IRC and ORC volumes, At      is the time step size, m,      is the IRC volume water mass, and cp      it the 4RC volume fluid specific heat.
The following equation is used to calculate the temperature in the IRC pipe section at the end of the time period being examined:
Tinc.r = Tinc + ATinc
                                             +

l Attachment i ST.llL. AIM 780 Page 100f 12 Where Times is the final IRC volume bulk Duld temperature,                                                          ,
Tinc           is the initial IRC volume bulk fluid temperature, and ATine is the IRC volume bulk Hulo temperature change.                                                     ;
2.c.h.2.4 ONC Pipe Section Temperature Change The evaluation of the temperature increase of the ORC ponion of the penetration is based on the assumption that the liquid and pipe are considered to be at the same temperature.
The following equation is used to evaluate the temperature increase for the liquid in the                           i ORC portion of the penetration:
4 onc
* At
         ## ~ (m.
* cf. . + m.,
* cr.n)      y, c Where       Il onc is the heat transfer rate between the IRC and ORC volumes, At       is the time step size,
: m. is tLe ORC volume water mass, cp,, is the ORC volume Guld specific heat,                                                               .
m, is the ORC piping steel mass, and c p.a is the ORC piping steel specific heat.
The following equation is used to calculate the temperature in the IRC pipe section at the end of the time period being examined:
Tosc.r = Tonc+ ATosc Where Toucy is the Anal ORC volume bulk fluid temperature, Touc           != d e initial ORC volume bulk Duid temperature, and ATonc is the ORC volume bulk Guld temperature change.
2.c.h.2.5 IRC Volume Change Due to Thermal Expansion The volume of the IRC pipe section following the expansion due to a temperature change is calculated based on the temperature change calculated in Equation 5 and the temperature dependent portion of Equation 4 as follows:
l'(T)inc . l'inc * (1 + 3
* a
* ATiac)                                                          Equation 7 Where V(T)inc is the final IRC pip. volume following thermal expansion, V ine         is the initial IRC pipe volume, u              is the piping material coefficient of thermal expansion, and ATine is the IRC volume bulk fluid temperature change.
2.c.h.2.5.1 ORC Volume Change Due to Thermal Expansion The volume of the ORC pipe section following the expansion due to a temperature change is calculated based on the temperature change calculated in Equation 6 and the temperature dependent ponion of Equation 4 as follows:
l'(T)onc a l'onc * (1 + 3
* a
* ATonc)                                                           Equation 8

Attachment 1 STill-AE5780 Pye 11 of 12 Where V(Tkmc is the final ORC pipe volume following thermal expansion,                                                           i Vonc     is the initial ORC pipe volume, u        is the piping material coefficient of thermal expansion, and                                                  ;
ATouc is the ORC volume bulk fluid temnerature change.                                                                 ;
2.c.h.3 Expansion Due to Pressure Changes                                                                                        ;
The expansion of the IRC and ORC pipe sections due to changes in pipe pressure are also                                          ;
based on Equatinn 4. The change in pipe volume due to expansion from a pressure                                                  !
change is combined with the volume change due to thermal expansion to determine the total volume of the system at the end of the time period being analyzed. The pressure in the system is determined iteratively based on conservation of mass by calculating the system mass following the volume changes. The AP used in Equations 9 and 10 is a                                                 ;
guessed value that is us;d to perform an iteration in the determina' ion of the total system mass as given by Equation 11. The iteration on pressure is performed until the total system mass for the time period being analyzed is essentially equal to the mass calculated for the previous time period.
2.c.h.3.1 IRC Volume Due to Thermal and Pressure Expansioit The total volume of the IRC section following the expansion o. the pipe due to the changes in pressure and temperature is calculated based on the volume calculated in Equation 7 and the pressure dependent portion of Equation 4 as follows:
V(P.T)inc = V(T)inc
* 1+1O                                                             Equation 9                         '
s     4   r         6s Where V(P, T)me is the IRC volume following the expansion due temperature and pressure increases, V(Thuc       is the final IRC pipe volume following thennal expansion, Do          is the pipe outside diameter, t            is the pipe wall thickness, AP           is the pressure change from beginning to end of the time step, and E           is the piping material modulus of elasticity.
I 2.c.h.3.2 OMC Volume Following Thermal ami Pressure Expansion Simihtrly, the volume of the ORC pipe section is determined due to expansion from changes in both temperature (Equation 8) and pressure (Equation 4) utilizing the following equation:
V(P.T)onc = V(T)onc
* 1 + $
* b
* Equation 10 4   r        E, When: V(P. T)one is the ORC volume following the expansion due temperature and pressure increases, V(T)onc     is the final ORC pipe volume following thermal expansion, D.          is the outside pipe diameter, t           is the pipe wall thickness,
                                                                        , ,.~,m     ,             ,_ .-.         - , - - - . - -

Attachment i ST IIL AIM 780 l' age 12 of 12 AP          is the pressure change from beginning to end of the time step, and E           is the piping material modulus of elasticity.
2.e.h.3.3 Mass Comparison in calculating the total system mass, the IRC and ORC fluid specific volumes are determined using the 1967 IFC formulation for ordinary water substanceH1 based on the temperature and estimated pressure at the end of the time period being analyzed. The total Guld mass in the pipe section is determined based on the IRC and ORC volumes calculated by Equations 9 and 10 as follows:
M = V(P T)inc     + V{ P.T)onc                                                        Equation 11 thnc         tunc Where M               is the Guld mass in the isolated pipe, V(P.T)inc is the IRC volume following the expansion due temperature and pressure increases, 1)inc       is the IRC Duid specific volume at the final temperature and pressure, V(P, T)one is the ORC volume following the expansion due temperature and pressure increases, and tk>nc       is the ORC Duid specine volume at the final temperature and pressure.
The total system mass for the time step being analyzed is then compared to the total system mass from the previous time step. The final system pressure is determined by iterating through Equations 9,10, and 11 for pressure until the system mass at the end of the time step is essentially equal to the mass of Guid in the pipe section at the beginning of the time step.
2.c.h.4 References
: 1. " Analysis of Over-pressure Conditions in an isolated Piping Section," C. J. Foley, Journal of Pressure Vessel Technology, pp. 253-257, May 1977.
: 2. "lleat Transmission," Third Edition, W.11. McAdams,1954.
: 3. "lligh Rayleigh Number lleat Transfer in a llorizontal Cylinder v.ith Adiabatic Wall," G.11. Schiroky and F. Rosenburger, International Journal of Ileat and Mass Transfer, Vol. 27, No. 4, pp. 630-633,1984.
: 4. "A Formulation of the Thermodynamic Properties of Ordinary Water Substance,"
International Formulation Committee (IFC), February 1967.
: 5. NUREG-0588," Interim Staff Position on Environmental Qualification of Safety-Releted Electrical Equipment," Revision 1}}